1. Field of the Invention
This invention pertains to apparatus for suppressing fires. More particularly, this invention pertains to such an apparatus for suppressing fires associated with vehicle tires.
2. Description of the Prior Art
From time to time, motor vehicles equipped with synthetic rubber tires may be at risk of exposure of the tires to fire or other extreme heat which may cause or contribute to ignition of the tires. For example, law enforcement vehicles are exposed to many threats during riots or other civil disturbances. Other peacekeeping vehicles (such as military vehicles) are subject to similar threats.
Unfortunately, a common threat exposure for such peacekeeping vehicles (and their occupants) is combustible materials which lie in the path of the vehicle or which are projected at the vehicle. A frequently encountered threat is a so-called Molotov cocktail which is a container (such as a glass bottle) filled with a flammable fluid (such as gasoline) and corked with a rag (that acts as a wick) which is ignited and then thrown at the vehicle with the intent of disabling the vehicle and causing serious injury or death to the occupants. When the bottle strikes the vehicle it shatters and the flammable liquid is ignited by the burning rag and spreads causing a large dangerous fire.
When a flame surrounds a tire, the exterior of the tire is exposed to the extreme heat of the flame. After a period of time (depending on the exposure and the amount of flammable material surrounding the tire as well as the type of the tire), the temperature could exceed the auto-ignition temperature of the tire material (approximately 350° C.) so that the tire fire becomes self-sustaining. In such an event, the fire is referred to as “deep seated” within the tire.
A deep-seated fire tire is an extremely dangerous event. The mass of the tire presents a substantial mass of combustible material which burns at extremely high temperatures (for example, 1,100° C.). Also, the fumes from the burning tire may be highly toxic. A deep-seated fire tire can quickly result in loss of a vehicle, its contents, and, tragically, its occupants.
During a threat condition (when flammable materials are being projected at a vehicle), the condition of the tires is not readily apparent to the occupants of the vehicle. The occupants' attention is focused externally on the threat. Also, the design of the vehicle may not permit inspection of tires. For example, specialty equipped riot control vehicles may have very small window openings precluding a field of view to the tires.
A tire may be exposed to flames in the initial stages of burning but not yet at a deep-seated condition. If the occupants can extinguish the fire at the tires before the fire becomes deep-seated, the danger associated with the fire can be substantially mitigated. However, once the fire becomes deep-seated, a substantial amount of fire suppressant material (normally requiring specialty fire equipment—such as full capacity fire engine) is needed to treat the fire in a manner sufficient to save the occupants or the contents of the vehicle. During peacekeeping functions, there are insufficient numbers of such specialty fire equipment to permit their sufficiently rapid response to address deep-seated fire threats of peacekeeping vehicles.
During a peacekeeping mission, police officers, military personnel or the like cannot safely exit their vehicles to inspect a potential tire fire and to treat such a fire with hand-held fire extinguishers or the like. Further, during such peacekeeping missions, such occupants cannot safely evacuate a vehicle to escape the dangers of a deep-seated tire fire. Such evacuations expose the occupants to a wide variety of dangerous threats during a riot condition. These threats include risk of substantial injury or death associated with projectiles, small arms fire and other hazards.
There is a need to equip such vehicles with fire suppression systems to extinguish a tire fire before it becomes deep-seated. It is an object of the present invention to provide such a system. It is a further object of the present invention to provide for a vehicle having a tire fire suppression system which is automatic. A still further object of the present invention is to provide a tire fire suppression system which is rugged in construction and has a quick and reliable mechanism for assessing the operational readiness of the system before entering a threat situation.